On the basis of which evidences D− glucose was assigned the following structure?

 

This is a Long answer type Questions as classified in NCERT Exemplar

Ans: The following evidences are used to assign the given structure:

Molecular formula; of the molecule glucose is found to be C₆H₁₂O₆. 

Straight chain structure: When an aqueous solution of glucose reacts with sodium amalgam, sorbitol (a hexahydric alcohol) is produced by the reaction.

Glucose after a prolonged time of heating with hydroiodic acid and red phosphorus at 100^oC gives a mixture of n-hexane and 2-iodohexane as two products. The reaction is depicted below:

Five hydroxyl groups: When glucose is acetylated in the presence of acetic anhydride, it produce

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This is a Long answer type Questions as classified in NCERT Exemplar

Ans: The following evidences are used to assign the given structure:

Molecular formula; of the molecule glucose is found to be C₆H₁₂O₆. 

Straight chain structure: When an aqueous solution of glucose reacts with sodium amalgam, sorbitol (a hexahydric alcohol) is produced by the reaction.

Glucose after a prolonged time of heating with hydroiodic acid and red phosphorus at 100^oC gives a mixture of n-hexane and 2-iodohexane as two products. The reaction is depicted below:

Five hydroxyl groups: When glucose is acetylated in the presence of acetic anhydride, it produces pentaacetate after the reaction. This confirms the presence of five -OH hydroxyl groups in the glucose molecule. The presence of two or more -OH groups on the same carbon atom is known to make the molecules unstable.

Presence of a single primary alcoholic group: When oxidized with concentrated nitric acid, glucose and gluconic acid, these all molecules yield the same product, dicarboxylic acid, saccharic acid, or glucaric acid. The main alcoholic group (CH₂OH) is always present at the end of the carbon chain in the molecule.

Presence of an aldehyde group: Glucose molecule combines with the hydroxylamine (NH₂OH) to produce glucose CHO oxime as the product. This implies that glucose has carbonyl (CHOH)₄ (>C=O) groups as it is needed to react in order to produce an oxime product.

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<p>This is a Long answer type Questions as classified in NCERT Exemplar</p><p><strong>Ans:&nbsp;</strong>The following evidences are used to assign the given structure:</p><p><strong>Molecular formula;</strong> of the molecule glucose is found to be C₆H₁₂O₆.&nbsp;</p><p><strong>Straight chain structure:</strong> When an aqueous solution of glucose reacts with sodium amalgam, sorbitol (a hexahydric alcohol) is produced by the reaction.</p><p>Glucose after a prolonged time of heating with hydroiodic acid and red phosphorus at 100^oC gives a mixture of n-hexane and 2-iodohexane as two products. The reaction is depicted below:</p><div class="photo-widget-full"><div class="figure"><picture><source srcset="" media=" (max-width: 500px)"><img src="https://images.shiksha.com/mediadata/images/1750940920phpOR4jSm.jpeg" alt="" width="655" height="135" loading="lazy"></picture></div></div><p>Five hydroxyl groups: When glucose is acetylated in the presence of acetic anhydride, it produces pentaacetate after the reaction. This confirms the presence of five -OH hydroxyl groups in the glucose molecule. The presence of two or more -OH groups on the same carbon atom is known to make the molecules unstable.</p><p>Presence of a single primary alcoholic group: When oxidized with concentrated nitric acid, glucose and gluconic acid, these all molecules yield the same product, dicarboxylic acid, saccharic acid, or glucaric acid. The main alcoholic group (CH₂OH) is always present at the end of the carbon chain in the molecule.</p><p>Presence of an aldehyde group: Glucose molecule combines with the hydroxylamine (NH₂OH) to produce glucose CHO oxime as the product. This implies that glucose has carbonyl (CHOH)₄ (&gt;C=O) groups as it is needed to react in order to produce an oxime product.</p>

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